Background: Individuals with pes planus tend to overuse the extrinsic foot muscles, such as the tibialis anterior (TA) and peroneus longus (PL), to compensate for the weakened intrinsic foot muscles, such as the abductor hallucis (AbdH). Furthermore, differences in weight-bearing can affect the activity of muscles in both the intrinsic and extrinsic foot muscles. To date, no study has compared the effects of the short foot exercise (SFE) and toe spread-out exercise (TSO) on intrinsic and extrinsic foot muscle activity and the corresponding ratios in different weight-bearing positions. Objects: To compare the effects of the SFE and TSO on AbdH, TA, and PL activity and the AbdH/TA and AbdH/PL activity ratios in the sitting and standing positions in individuals with pes planus. Methods: Twenty participants with pes planus were recruited. Surface electromyography was used to assess the amplitudes of AbdH, TA, and PL activity. Participants performed both exercises while adopting both the sitting and standing positions. Results: No significant interaction between exercise and position was found regarding the activity of any muscle or ratio of the activity, except for PL activity. We observed a significant increase in AbdH activity during the TSO compared to the SFE, and no significant difference in TA and PL activity between the two exercises. AbdH, TA, and PL activity were significantly higher in the standing position than in the sitting position. Furthermore, the AbdH/PL activity ratio significantly increased in the sitting position, although there was a significant increase in AbdH activity in the standing position. Conclusion: In individuals with pes planus, we recommend performing the TSO in the sitting position, which may increase the activity of the AbdH while concurrently decreasing the activity of the TA and PL, thus strengthening the AbdH.

Background: Changes in foot sole shape can result in plantar muscle weakness, lack of proprioception, increased ankle instability, and an inability to balance. Objectives: To investigated whether different floor surfaces influenced the effect that short-foot exercises have on the foot core system of healthy individuals. Design: Pretest-posttest control group experimental design. Methods: This exercise shortens the length of the foot by raising the medial longitudinal arch, strengthening the intrinsic muscle of the sole, and maintaining the shape of the medial longitudinal arch. Results: There was a significant difference in the angle of the medial longitudinal arch in the mat exercise group (MEG) and vibration exercise group (VEG) before and after the intervention (P<.05). As the arch angle decreased, the arch height increased. Post hoc analysis showed that there was no difference between the floor exercise group (FEG) and MEG or between the MEG and VEG (P>.05). In terms of the weight distribution index (WDI, there was a significant difference in the MEG and VEG (P<.05) but not in the FEG before and after the intervention (P>.05). The post hoc analysis results showed that there was no difference between the FEG and MEG (P>.05). Conclusion: Various methods to improve the strength of intrinsic muscles of the sole are more effective than no stimulation, and that short-foot exercise combined with sensory stimulation can be recommended for maintaining and increasing the medial longitudinal arch.

Background: Short foot exercise, which is an intrinsic foot muscle exercise proposed by the foot core system, is used to improve the strength of intrinsic foot muscles and sensory input and function of the foot. However, there is a lack of studies that assessed the improvement in foot function after short foot exercise in patients undergoing rehabilitation after a modified Broström operation of the ankle joint. Objectives: To investigate the effects of short foot exercise on intrinsic foot muscle cross-sectional area and balance ability in patients who had undergone a modified Broström operation of the ankle joint. Design: A single blind, randomized controlled trial. Methods: Sixteen patients who were undergoing ankle rehabilitation exercises following the modified Broström operation were randomized into two groups. General physical therapy, short foot exercises, and ankle rehabilitation programs were performed in the experimental group (n=8), whereas general physical therapy and ankle rehabilitation programs were performed in the control group (n=8). For outcome measures, the intrinsic muscles of the foot were imaged using the Sonimage HS1 musculoskeletal ultrasound system. The Y-balance test and RS-foot scan system were used to confirm dynamic balance ability and static balance ability. Results: The cross-sectional area of the abductor hallucis and dynamic balance ability significantly improved in the experimental group that underwent short foot exercise compared to the control group (P<.05). In contrast, static balance ability was not significantly different between the two groups (P>.05). Conclusion: Short foot exercise successfully increased the cross-sectional area of the abductor muscle and improved dynamic balance after a modified Broström operation

Background: Flexible flat foot is that the medial longitudinal arch collapses in weight bearing and returns normal arch when weight is removed and the weight bearing shifts toward medial part of the foot, which can cause pathological problems in the alignment of the lower extremities and the entire body. Objective: To compare the foot pressure for adults with flexible flat foot. Design: Quasi-Experimental Study Methods: 24 participants with flexible flat foot were recruited and were randomly divided into Visual feedback Short Foot Exercise (VSFE) group and Short Foot Exercise (SFE) group. To compare changes of foot pressure about pre and post intervention, the contact pressure measurement was conducted. Results: In the VSFE, significant differences were observed for the foot pressure of the 1st toe, 1st, 3rd and 4-5th metatarsal, midfoot, medial and lateral heel (p<.05). The foot pressure of the 3rd and 4-5th metatarsal, midfoot showed significant differences in the SFE (p<.05). The contact pressure of the 1st toe, 3rd metatarsal showed significant differences between the groups. Conclusions: Visual feedback short foot exercise can be useful for moving the pressure from medial to lateral part, and can prevent possible pathological problems.

Background: The MLA is supported by both the abductor hallucis (ABH) and the extrinsic muscles. Insufficient muscular support may lower the MLA when the body’s weight is applied to the foot. The short foot exercise (SFE) is effective in increasing the height of the MLA for people with flat feet. Most of the research related to the SFE has simply evaluated the efficiency of the exercise using enhanced ABH electromyography (EMG) activation. Since the tibialis anterior (TA), peroneus longus (PER), and ABH are all involved in supporting the MLA, a new experiment design examining the EMG of the selected muscles during SFE should be applied to clarify its effect. Objects: Therefore, this study aimed to clarify the effect of the SFE in different ankle position on the MLA angle and the activation of both the intrinsic and extrinsic muscles and to determine the optimal position. Methods: 20 healthy subjects and 12 subjects with flat feet were recruited from Yonsei University. The surface EMG and camera were used to collect muscle activation amplitude of TA, PER, and ABH and to capture the image of MLA angle during SFE. The subjects performed the SFE while sitting in three different ankle positions—neutral (N), dorsiflexion (DF) at 30 degrees, and plantar flexion (PF) at 30 degrees. Results: ABH EMG amplitudes were significantly greater in N and DF than in PF (p<.05). Muscle activation ratio of TA to ABH was the lowest in PF (p<.05). MLA angle in both groups significantly decreased in PF (p<.01). The TA and ABH was activated at the highest level in DF. However, in PF, subjects significantly activated the ABH and PER with relatively low activation of TA. Conclusion: Therefore, researchers need to discuss which SFE condition most effectively use the arch support muscle for flat foot.

Background: Short foot exercise (SFex) is often prescribed and performed in the sport and rehabilitation fields to strengthen intrinsic foot muscles. However, SFex is difficult to perform because of lack of feedback methods. Objects: The aim of this study was to compare the effects of SFex with and without electromyography (EMG) biofeedback on the medial longitudinal arch (MLA) of healthy individuals who maintained a static standing position. Methods: All participants (14 males and 12 females) were randomly divided into two groups (biofeedback and non-biofeedback groups). The EMG activity of the abductor hallucis (AbdH) and tibialis anterior (TA) and the MLA angle on the dominant leg side were measured with the participant in the standing position in the pre- and post-intervention conditions. The intervention session consisted of 15 minutes of SFex with (biofeedback group) or without (non-biofeedback group) EMG biofeedback. The groups were compared using two-way repeated measures analysis of variance. Results: The post-intervention activities of the AbdH muscle (p<.05) and the AbdH/TA ratio (p<.05) were significantly greater in the biofeedback group than in the non-biofeedback group. The activity of the TA (p<.05) and the MLA angle (p<.05) in the biofeedback group were significantly lower in the post-intervention condition than in the pre-intervention condition. Conclusion: The present findings demonstrate that the combination of SFex and EMG biofeedback can effectively facilitate the muscle activity of the AbdH and strengthen the medial longitudinal arch.

The aims of this study were to investigate the correlation between the electromyographic (EMG) activity of the abductor hallucis (AbdH) and the amount of pressure measured by a pinch gauge (PG), and to compare the EMG activity of AbdH and the pressure measured by the PG during short foot (SF) exercise in subjects with pes planus and in subjects with a neutral foot alignment. Fourteen subjects were recruited for this study (pes planus group=7; neutral foot alignment group=7). A surface EMG was used to collect AbdH activity, and a PG was positioned under the first metatarsophalangeal joint to measure the pressure produced by the first metatarsal head during the SF exercise. The AbdH activity and the pressure measured by the PG showed a positive good correlation (r=.80, p<.05). The EMG activity of the AbdH and the pressure measured by the PG were significantly lower for subjects with pes planus than for subjects with a neutral foot alignment (p<.05). Based on these findings, the PG can be recommended as an effective instrument for evaluating the performance of the AbdH. It may also be beneficial for monitoring how well the SF exercise is performed, and for providing visual feedback to patients with pes planus during SF exercise in a clinical setting.